docstr: make sure freq2note(439) == A4 
docstr_tok: ["make","sure","freq2note","(","439",")","==","A4"]
code: def test_freq2note_under(self):
      "make sure freq2note(439) == A4"
      self.assertEqual("A4", freq2note(439))
  
imports: from __future__ import unicode_literals
  from aubio import note2midi, freq2note, note2freq, float_type
  from numpy.testing import TestCase
  from _tools import parametrize, assert_raises, skipTest
label_desc: Use image node_id 2 for calling the freq2note_simple_test obj's underlying member method code with example usage: obj.test_freq2note_under() without return types